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Re: [Chimera-users] using a marker file to zone a volume from python prompt
by Thomas Goddard 29 Jan '07

29 Jan '07

Hi Jeff, I've attached a script that opens a density map and a Chimera marker file and writes a new volume corresponding to a zone around the markers. It does not require showing the Chimera user interface to do this. Perhaps you don't need this now (I just got your follow-up email.) but perhaps you will find it useful in writing other scripts. Karin Gross at Max Planck Institute of Biochemistry has written a Chimera extension to slice tomograms at arbitrary angles. I saw it when I visited Munich in December. They also were planning on allowing marker placement on those planes. The volume planes tool could be made to average neighboring planes. Currently it simply displays a NxMx1 subvolume in solid rendering mode. Since there is no existing code in Chimera to support averaging adjacent planes that would have to be added. Probably the easiest solution is to add the adjacent planes in Python and create a new single plane volume on the fly. Tom Jeff wrote: > thanks Tom, > > I will try that. alongside that, is there a way for me to run a 'zone' > function and save a subregion from a python command line (no chimera > launched, just import a library?)? > > I have used the volume planes tool to generate a marker set of a > membrane, it was handy. But, it only handles orthogonal directions, it > can't provide an arbitrary interpolant (which is a large reason I rely > heavily on IMOD's slicer tool); this functionality would be very useful. > A second addition to the volume planes tool would simply be allowing > averaging several slices together (reduces noise) in the direction > normal to the planes, which may already be there (the documentation > online said something about this feature, but it wasn't clear to me) > > it the volume planes tool were able to handle an arbitrary > view/interpolant, then I wouldn't have to depend on the slicer tool, and > the previous request about rotating markers that was related to that > requirement (different features available in different slicer > orientations in IMOD, necessitating a rotation prior to visualization > with the volume planes tool in chimera, thus requiring old marker set > from original volume to be rotated to be used in new volume, etc) would > effectively be voided > > > -Jeff # ---------------------------------------------------------------------------- # Save a volume zone around a given set of markers as a new volume file. # def save_zone(volume_path, markers_path, radius, volume_out_path): # Read zone points atoms, bonds = marker_set_atoms_and_bonds(markers_path) from chimera import Xform xform = Xform() # Identity transform for marker points from SurfaceZone import path_points points = path_points(atoms, bonds, xform) from VolumeData import open_file_type vol = open_file_type(volume_path, 'mrc') # Get containing volume subregion ijk_min, ijk_max = containing_subregion(vol, points, radius) from VolumeData import Grid_Subregion subvol = Grid_Subregion(vol, ijk_min, ijk_max) # Make new volume with zeros outside radius from VolumeViewer import zone_masked_grid_data masked_vol = zone_masked_grid_data(subvol, points, radius) # Write new volume from VolumeData.mrc import write_mrc2000_grid_data write_mrc2000_grid_data(masked_vol, volume_out_path) # ---------------------------------------------------------------------------- # def marker_set_atoms_and_bonds(markers_path): from VolumePath.markerset import load_marker_set_xml msets = load_marker_set_xml(markers_path) atoms = [] bonds = [] for mset in msets: atoms.extend(map(lambda m: m.atom, mset.markers())) bonds.extend(map(lambda l: l.bond, mset.links())) return atoms, bonds # ---------------------------------------------------------------------------- # def containing_subregion(vol, points, radius): from VolumeViewer import points_ijk_bounds, clamp_region ijk_min, ijk_max = points_ijk_bounds(points, radius, vol) ijk_min, ijk_max = clamp_region((ijk_min, ijk_max, None), vol.size)[:2] from math import floor, ceil ijk_min = map(lambda x: int(floor(x)), ijk_min) ijk_max = map(lambda x: int(ceil(x)), ijk_max) return ijk_min, ijk_max # ---------------------------------------------------------------------------- # volume_path = '/usr/local/src/chimera-demos/volume/examples/tricorn_map.mrc' markers_path = '/usr/local/src/staff/goddard/chimera/devel/ZoneScript/test.cmm' radius = 5 volume_out_path = '/usr/local/src/staff/goddard/chimera/devel/ZoneScript/test.mrc' save_zone(volume_path, markers_path, radius, volume_out_path)

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access to pdb parser
by Jean Didier Pie Marechal 29 Jan '07

29 Jan '07

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Re: [Chimera-users] zone tool and volume rendering
by Thomas Goddard 29 Jan '07

29 Jan '07

Hi Jeff, The volume dialog "zone" feature does not work with solid (volumetric) rendering. The current implementation just hides surface triangles having vertices outside the given range so it only works on surfaces. When you use volume dialog File / Save map as... it makes a copy of the data with grid values set to zero outside the radius. Creating a copy of the map in memory or masking the map for use with solid rendering are not currently supported. We wish to add this in the future and it should not be hard to achieve although performance when changing the radius will be significantly worse than with the current surface zoning. The documentation does not mention this limitation and I will update the volume dialog description to describe it. Tom Jeff wrote: > hi Tom, > > is there a way to get the zone tool to operate when doing a solid/volume > rendering - in surface mode, if you set a zone radius, let's say 40 A, > you'll get a region that extends 40 A around the selected marker(s); > however, in 'solid' mode, it appears I get the entire orthogonal region > in the volume that encloses the markers plus that radius. thiis is > problematic if the markers span the hypotenuse of the volume; in that > case, zone with volume/'solid' appears to more or less display the > entire volume rather than just the surrounding region as in 'surface mode' > > do I have a buggy version? this is a recent release, but I've had this > happen with previous releases > > -jeff

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Re: [Chimera-users] chimera startup problem
by Greg Couch 29 Jan '07

29 Jan '07

Just a FYI to the list, the problem here was an ancient OpenGL graphics driver. Upgrading it made the problem disappear. I'll be adding an entry to our Graphics Driver bugs web page, <http://www.cgl.ucsf.edu/chimera/graphicsbugs.html> with a few more details. - Greg ---------- Forwarded message ---------- Date: Tue, 23 Jan 2007 12:25:41 -0500 From: Chen Xu <xuchen66(a)gmail.com> To: chimera-users(a)cgl.ucsf.edu Subject: [Chimera-users] chimera startup problem Dear List, after upgrading to 1.2304 (1.2303 freeze the computer after several minute loaded with a volume pdb file) , I have problem to start it up on (RedHat): agnieszka@raptor ~]$ chimera Error starting chimera: ValueError: attempt to create string with null pointer (see reply log for Python traceback info) Traceback (most recent call last): File "/sware/chimera/chimera-1.2304/share/__main__.py", line 59, in ? value = chimeraInit.init(sys.argv) File "CHIMERA/share/chimeraInit.py", line 255, in init tkgui.initializeGUI(exitonquit) File "CHIMERA/share/chimera/tkgui.py", line 2407, in initializeGUI File "CHIMERA/share/chimera/tkgui.py", line 2368, in createApp File "CHIMERA/share/chimera/tkgui.py", line 1784, in __init__ File "CHIMERA/share/chimera/tkgui.py", line 1811, in makeGraphicsWindow ValueError: attempt to create string with null pointer any help?

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Slow rendering in FC6
by Thomas Goddard 29 Jan '07

29 Jan '07

On Yifan's linux system a large molecule takes a second to redraw and gradually renders from one side to the other. Turned out he did not have the NVIDIA graphics driver installed, so MESA software rendering was being used. Determined this using linux "glxinfo" command. Solution was to install graphics driver. -------- Original Message -------- Subject: problem of running Chimera in FC6 Date: Sun, 28 Jan 2007 13:05:20 -0800 From: Yifan Cheng To: goddard(a)cgl.ucsf.edu Hi Tom, I have a question about running Chimera in Linux FC6 system and wondering if you could help me out? I have Linux boxes running FC6, with a Gigabyte GV-NX76G256D-RH Geforce 7600GS 256MB video card. But somehow the Chimera keep refreshing with any movement in the model or map I loaded into it. It runs this way in both thousands color mode as well as in millions color mode. This video card is not Quadro type and has no stereo function, but I thought this shouldn't matter. Do you have any idea what might be the problem? Thanks a lot for your help. best, Yifan

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Re: [Chimera-users] align different scale models
by Thomas Goddard 29 Jan '07

29 Jan '07

Hi Pu, The PDB file uses units of Angstroms. To specify the spacing between grid planes of your EM map, open it in Chimera, then use menu entry Features / Origin and Scale from the volume dialog. The "voxel size" values listed indicate the size of one grid cell in the density map which is equivalent to the grid spacing. You can change the values and press Return (or Enter) key and the map will be shown at the new scale. Enter the values in Angstroms. (Chimera does not know what units you are using but all data sets must use the same units if you want them to be displayed at the correct relative scales.) The map file is not modified. To save the new scale you either can save a Chimera session (File / Save session as... on the main Chimera window) or save a new copy of the map (File / Save map as... on the volume dialog). Tom P Qian wrote: > Hi Tom, > > I have question to ask you about alignment of PDB model and EM density map. > > When I open both EM density map and its corresponding PDB model, I found they > have different size. I think that is due to different scale they are using. My > question is: Is it possible for me to re-scale them individually so that they > can match each other. I cannot do it at the momemt because zoom function will > affect all data loaded, not only active data but also unactive one. I'm trying > to produce a EM density map which has same scale with PDB model to solve it, > but if Chimera could do it as well, it will be helpful. Thanks > > Best regards > > P. Qian > > Dr. Pu Qian > Physics Department > The University of Sheffield > Hicks Building > Hounsfield Road, S3 7RH > UK >

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Re: [Chimera-users] using a marker file to zone a volume from python prompt
by Thomas Goddard 29 Jan '07

29 Jan '07

Hi Jeff, I understand your problem. I think you can handle the large data sets interactively using the "precomputed subsample" feature of the volume dialog. As you mentioned you need to create smaller binned versions of your data. Then you open your full size map in Chimera but do not display it. Then you use Features / Precomputed Subsamples and add the binned file (ie. subsampled data). Then when you display the data with step sizes larger than 1 where it can use the binned data it will use the binned data. In this way Chimera never needs to open the full data if you only display at binned step sizes. You can then use the zone or subregion box tools to specify a smaller piece of the map and then use the volume dialog "File / Save map as" menu entry. That always says at full resolution, so the needed part of the full size map will be read when you do that. There is a Chimera script for creating the binned data (chimera/share/VolumeProcessing/downsize.py) described in the Volume Viewer documentation in the Chimera User's Guide: http://www.cgl.ucsf.edu/chimera/docs/ContributedSoftware/volumeviewer/volum… Another useful tool for handling tomograms that are too large to display in Chimera at full resolution is the Volume Planes module that can be downloaded from the Chimera experimental features page http://www.cgl.ucsf.edu/chimera/experimental/experimental.html When you display just one plane at a time, Chimera only loads that plane from the map file (for most map file formats, e.g. MRC). This can allow you to flip through the planes at full resolution while having just a limited amount of data in memory at any one time. Tom ---- Date: Jan 29, 2007 hi Tom, is it possible for me to use a (previously generated) chimera marker file to zone and save a region from a volume map from a python prompt, without launching chimera? A lot of volumes I use are simply too big to handle in chimera, and if I chop up large volumes, I might have filaments running across the borders that I cut, etc. When I have done such 'chopping out' of subvolumes, it is often difficult for me to figure out which filaments I care about (or where they are ...) a priori. One solution I was thinking of is to use a several-times binned file to generate a marker file using chimera, and then to use the zone tool from a python prompt on the unbinned volume, without having to launch chimera and try to actually visualize the full, unsegmented volume. can I do this? (or, does this question make sense?) thanks, -Jeff

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Color using Beta factor
by Batsal Devkota 24 Jan '07

24 Jan '07

Hi, Is it possible to color the atoms according to their beta factor? Also, is there anyway I can search "the chimera-user archives"? batsal. -------------------------------------------------- Batsal Devkota Graduate Student, School of Biology GeorgiaInstitute ofTechnology Atlanta, GA 30332-0400

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Re: [Chimera-users] defining rotation of a chimera markers file
by Thomas Goddard 24 Jan '07

24 Jan '07

Hi Jeff, Attached is a Python script to rotate Chimera markers about the origin using specified Euler angles. You open the script with Chimera menu entry File/Open... to apply the rotation which is specified at the end of the script. Tom Jeff wrote on Wed, Jan 24, 2007: thanks Tom (and Elaine), did not have the chance to reply yet. I have not done a whole lot w/ Euler angles in general but do know there are several conventions - seems like one for each package... As for a convention, the reason this came up is b/c the slicer tool in the IMOD viewer allows the user to rotate the volume according to the angles listed in the slider tool window. I use IMOD quite a bit to look plane by plane in various orientations in a reconstruction, and I'd like to be able to go back and forth with chimera (the IMOD extension in chimera only cycles through z; for an arbitrary plane, one would have to rotate the volume and reload into chimera). So, the convention used by IMOD would be preferred by me, for practical reasons. Here's the manpage for 'rotatevol' in IMOD, which mentions the convention: http://bio3d.colorado.edu/imod/doc/man/rotatevol.html 15 lines of code is fine; I might actually be able to dissect something that size and use it to learn. If I had a script I could do it through a python prompt, which would get me started. A command in chimera would be nicer, but not required (same goes for a graphical interface). You know, if I knew how to import the marker positions into an array in python, I could probably play with this myself - I guess I would also have to know how to write out the file too, and I'd have to brush up on my rotations. I have scanned through the contents of a marker file (`cat foo.cmm | less`, for example) and realize it is text, but I don't have enough familiarity with python to parse it into something useful. If you were to write a simple script, for basic I/O of a marker file (or tell me how to go about that) and a rotation matrix / execution as an example, I could probably run with that. For instance, if I do some things in EMAN or SPIDER, I might be able to adjust the convention when needed without further assistance. At some point, I'd like to know enough to make extensions for chimera, but lack the time to plug away at it. -Jeff # ------------------------------------------------------------------------------ # Rotate all markers in the active path tracer marker set. # def rotate_markers(xform): from VolumePath import volume_path_dialog d = volume_path_dialog() if d == None: return # No marker sets exist. ms = d.active_marker_set if ms == None: return # No marker set chosen in dialog. from chimera import Point for m in ms.markers(): xyz = m.xyz() # Python tuple txyz = xform.apply(Point(*xyz)).data() m.set_xyz(txyz) # ------------------------------------------------------------------------------ # Convert Euler angles to an equivalent Chimera transformation matrix. # # Angles must be in degrees, not radians. # # Uses the most common Euler angle convention (the chi-convention) described at # # http://mathworld.wolfram.com/EulerAngles.html # def euler_transform(phi, theta, psi): from chimera import Xform, Vector xf1 = Xform.rotation(Vector(0,0,1), phi) # Rotate about z-axis xp = xf1.apply(Vector(1,0,0)) # New x-axis xf2 = Xform.rotation(xp, theta) # Rotate about new x-axis zp = xf2.apply(Vector(0,0,1)) # New z-axis xf3 = Xform.rotation(zp, psi) # Rotate about new z-axis xf = Xform() xf.premultiply(xf1) xf.premultiply(xf2) xf.premultiply(xf3) return xf # ------------------------------------------------------------------------------ # xf = euler_transform(30, 60, 45) rotate_markers(xf)

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Problem loading trajectories ....
by sharada 23 Jan '07

23 Jan '07

Dear Chimera-users, Hello, I am a brand new entry into this forum. I have started using chimera recently. I use Gromacs for my molecular modeling work. Till I become friendly with chimera I need your valuable suggestions and cooperations. I request you to kindly bear with my very silly doubts and questions. Let me explain my problem. I have a protein of 35 residues and have simulated in a box of water for 10ns. My protein has charge so in order to neutralize it I have added counterions randomly placed them in the solvent(water). The counter ions that I am adding are Cl- ions. I have created a *.trr file of the tracjectory for this 10ns. I would like to visulaize this trajectory using chimera. I am using Tools /MD/Ensemble Analysis /MD Movie to load the trr file. when I do so I am getting the following error: Unknown molecule type: CL- TypeError: __len__() should return an int (see reply log for Python traceback info) Traceback (most recent call last): File "/usr/local/chimera/share/__main__.py", line 59, in ? value = chimeraInit.init(sys.argv) File "CHIMERA/share/chimeraInit.py", line 318, in init tkgui.eventLoop() File "CHIMERA/share/chimera/tkgui.py", line 2675, in eventLoop File "CHIMERA/lib/python2.4/lib-tk/Tkinter.py", line 965, in mainloop self.tk.mainloop(n) File "CHIMERA/lib/python2.4/site-packages/Pmw/Pmw_1_2/lib/PmwBase.py", line 1751, in __call__ File "CHIMERA/lib/python2.4/site-packages/Pmw/Pmw_1_2/lib/PmwBase.py", line 1814, in _reporterror File "CHIMERA/lib/python2.4/site-packages/Pmw/Pmw_1_2/lib/PmwBase.py", line 1377, in displayerror File "CHIMERA/lib/python2.4/site-packages/Pmw/Pmw_1_2/lib/PmwBase.py", line 1747, in __call__ File "CHIMERA/share/chimera/baseDialog.py", line 231, in <lambda> File "CHIMERA/share/chimera/baseDialog.py", line 473, in OK File "CHIMERA/share/Trajectory/EnsembleLoader.py", line 87, in Apply File "CHIMERA/share/Trajectory/formats/Gromacs/__init__.py", line 56, in loadEnsemble File "CHIMERA/share/Trajectory/formats/Gromacs/__init__.py", line 67, in loadEnsemble File "CHIMERA/share/Trajectory/formats/Gromacs/Gromacs.py", line 30, in __init__ File "CHIMERA/share/Trajectory/formats/Gromacs/Gromacs.py", line 218, in __init__ File "CHIMERA/share/Trajectory/formats/Gromacs/Gromacs.py", line 229, in _readHeader File "CHIMERA/lib/python2.4/xdrlib.py", line 194, in unpack_fstring if j > len(self.__buf): TypeError: __len__() should return an int What exactly is the problem ? How to solve it ?

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